It is known that cerium oxide treatment of a metal improves the corrosion resistance due to the formation of a protective oxide film which acts as an active protective layer on the metal surface.
Adhikari et al in Electrochimica Acta, Vol 53, issue 12, pp 4239-4247 studies anticorrosion properties of a coating comprising modified polyaniline dispersed in polyvinylacetate on carbon steel.
Zhitomirsky in Surface Engineering, Vol 20, issue 1, pp. 43-47 discloses electrodeposition of films comprising ceria and the cationic polymer polyethylenimine.
Corrosion inhibiting coatings according to the state of the art often use compounds which are known to cause environmental problems and/or health problems for users. Examples include chromium compounds.
Y. Gao et al in Transactions of the Institute of Metal Finishing vol 84, no 3, 2006, pp 141-148 discloses corrosion protection of zinc electroplated steel. The corrosion inhibiting coating is a coating comprising either gelatine or albumin as well as dichromate. Also an alternative coating comprising gelatin and cerium trichloride is disclosed. It is concluded that the ability of cerium trichloride to stabilize protein formulations against putrefaction is questionable and that its adoption would require an associated stabilizer.
U.S. 2004/0028820 discloses coating of aluminum using cerium ions in the presence of an oxidizing agent. The preferred cerium-based coatings comprise cerium oxide, hydrated cerium oxide, or forms of cerium hydroxide after coating. The coating bath optionally contains animal gelatin, glycerol, or other organic additive to improve coating uniformity and corrosion resistance. It is speculated that the gelatin functions to modify the nucleation and growth sites.
Mussel adhesive protein (MAP) is formed in a gland in the foot of byssus forming mussels, such as the common blue mussel (Mytilus edulis). U.S. Pat. No. 5,015,677 as well as U.S. Pat. No. 4,585,585 disclose that MAP has very strong adhesive properties after oxidation and polymerization, e.g. by the activity of the enzyme tyrosinase, or after treatment with bifunctional reagents.
J. H. Waite et al in The Journal of Adhesion, vol. 81, 2005, pp 297-317 reviews adhesive proteins from mussels.
Lee et al in Science, vol 318, 2007, pp 426-430 discloses dopamine self-polymerization to form thin, surface-adherent polydopamine films onto a wide range of inorganic and organic materials, including noble metals, oxides, polymers, semiconductors, and ceramics.
WO 03/008376 discloses conjugation of DOPA moieties to various polymeric systems.
A. Statz et al in Biofouling, vol 22, no 6, 2006, pp 391-399 concerns marine antifouling and fouling-release performance of titanium surfaces coated with a polymer consisted of methoxy-terminated poly(ethylene glycol) conjugated to the adhesive amino acid DOPA and was chosen based on its successful resistance to protein and mammalian cell fouling. It is concluded that this polymer may be effective in marine antifouling and fouling-release applications.
CN 101658837 discloses preparation of an anticorrosive film for metal surfaces. The film comprises dopamine.
WO 03/080137 discloses a method for attaching two surfaces using a protein and periodate ions.
In the prior art there is still a need for an improved corrosion protection.